CA2134219A1 - Orthopedic casts - Google Patents

Abstract

Orthopedic casts which comprise a casting polymer of melting point Tm which is preferably from 40 to 60 ·C. The casting polymer is preferably coated onto an elastically deformed fabric, so that the cast recovers when heated to a temperature above Tm. The cast preferably has an air flow permeability of 10 to 35 %
resulting from the presence of apertures of area 0.01 to 0.08 cm2, so that it can be rapidly heated by means of a hot air gun.
Preferred casting polymers comprise a side chain crystallizable (SCC) polymer, particularly one containing units derived from styrene or another high Tg monomer. The addition of certain other polymers, e.g. an ethylene/vinyl acetate copolymer, and/or certain inorganic fillers, e.g. calcium carbonate, wollastonite and talc, results in improved balance of tensile strength and elongation.

Description

wo93/21967 ~ ? ~ j~ rcr/usg3/03g62 ORTHOPEDIC CASTS

BACKGROUND OF T~ INVENTION
s This invention relates to or~hopedic casts.
It is well known to make orthopedic casts, splints, supports, braces, shields, wound covers, and like orthopedic devices (all of which are ref~red to herein simply as "casts") from calcined gypsum (Plaster of PaIis) or from a polymer which is formed into shape while hot and hardens on cooling. The term "casting composition" is used herein to denote a polymeric composidon which can be for~ into shape while hot and har~ens -- on cooling. The casting composi~on can compnse a single polymer or a 1mxtu~e of two or mo~e polyme~s, and can contain additional ingr~dien~s such as inorgan;c fillers. ~e known casts can contain a flexible support, which may be elastic, for example a fabnc or a foam shee~ Refe~ence should ~e made ~or example to US Patent Nos. 3,692,023 (Phillips), 3,728,206 ~Buese), 3,809,600 ~OIl~, 4,231,356 (US~ ra)9 4,404,333 (Watanabe), ~,473,672 (Green), 4,668,563 (Buese), 4,784,123 (Ro~eson), 4,912,174(Grouilles), and 4,9469726 (Sandvig), British Pa,tent No, l,5227399 (Hexcel) andEu~pean patent publica~on 0,110,860 (Luxilon~. The dis~losure c>f each of d~ose documents is inco~porated he~ein by r~ference. However, ~e know~l casts do not prwide an entirely saasfactoIy combin~on of ~noldability at te~pelatures which aIe well tolerated by the r~pient of the cast, rapid hardening, and, after hardening, adequate strength, light weight, good breathability, water resistance, and ~ansparency to x-rays.

25 ~
We have discov~d a number of ~p~rtant improvements in cas~ng composi~ons and in the construction, applica~on and use o~ orthopedic casts, e~ly on human patients, but also on animals. Ihese discoveries can also be utili~ed in equivalent and 30 related fields, whe~e ~e same or similar casts are applied ~o inanimate subs~ates and where the casting composi~ons are used for molding gener~lly.
In a first aspect~ the present invendon provides an a~cle which is (a) suitable for use as an orthopedic cast, or can be converted into an ar~cle suitable f~r use as ~n 35 ~r~opedic cast, (b) comprises a cas~ng composition which comprises a polymer having a crystalline melting point Tm ~referred to herein as the casting polym~), (c) has a first stable con~îgoraaon a~ temperatures below Tm~ (d) becomes moldable when heated tO a temperature above Tm and adopts a second stable configura~ion when cooled wo 93/21967 PC~/US93/03962 3 ~ ~ 2 to a temperature below Tm after being molded, and (e) has at least one of the following characteristics (1) the casting polymer has a Tm of 40 to 55C, a Young's Modulus at 25C
of at least 22,000 psi (1540 kg/cm2) and a melt viscosity at 65C of less S than 8.5 x 105 poise, (2) at least a part of d~e a~cle is (i) heat-recoverable, and (ii) when heated to a tempe~ re above T"~ in the absence of res~ , recovers so that at least one dimension thereof de~eases from a first value x to a second value y which is at most 0.95 x, (3) when the a~cle is heated to a temperanlre above Tm and then cooled to ~m-10)C at a r~te o~ 10C per minute, the casting c~mposi~on recrystallizes not mo~e ~an 2 ~utes after it has cooled ~ Tm~

(4) at least a part of the ~cle has a plurali~y of apert~s d~rough its thickness, each of dle apertures having an area of 0.01 to 0.08 cm2, (5~ ~ at least a part of the article has an air flow pe~neabili~r of tO to 3~%, (6) th~ casting polymer c~mprises an SCC polymea, and (7) the cast comprises SA) a first component which (i) has an open cross-section and (ii) com~es the casting c~nposition, and ~33 a second component which (i) fo~ns a closed cr~ss-secti~n with the first component and (ii) is elastomeric when dle article is in its first configuranon andfor when the aracle is in its second configura~ion In a second aspect, the inven~ion provides a process for fnrrning an orthop~c cast around a paaent c~r fo~ prep~g an ar~icle w~ch is suitable for use as an orthopedic çast, which process comprises (~ hea~ng ~n arnele acco~ding to the first aspect of dle invell~on ~ a tempeIature above Tm at which ~e ~cle is mo~dable;
(B) molding d~e ardcle, whil~. it iS at a temperature at which it is moldable, into a second configuration, ~d (~ cooling dle ar~cle to ~ender the second configura~on s~able.

In a third aspect, the inven~on provides novel compositions which comprise (A) a random copolymer which compnses (i) at least 30~ of units having a crystalline mel~ing point (~ the copolymer) of Tm C and daivable f~m at least one n-alkyl-acryla~e or n-aL~cyl methaclylate whe~ein the n-alkyl group contains 14 to 50 carbon atoms, and WO93/21967 æ~ 2l~i PC~/US93/03962 (ii) 7 to 70% of units de~ived from at least one monomer, said monomer being one which, when homopolymenzed, results in a homopoly ner having a glass transiuon point Tg which is at least (Tm +10)C:, and (B) a random copolymer which comprises (i) at least 30~o of units denved from ethylene and (ii) 7 to 709'o of units derived fr~m an ethylenically unsaturated monomer containing at least one polar gr~up, the ratio of A tO B being from 0.25 to 4.

Ln a fourth aspect, the invennon provides novel compoidons which comprise (A) an SCC polymer which has a molecular weight o~less than 15,000 and which con~ns 2 to 10%, pre~erably 3 to 7%, of units de~ived from acrylic o~ medlacrylic acid, and (J3~ an ethylene/vinyl acelate cops~lymer which con~ns 25 to 40% of units derived fiom ~yl acetate, a~d preferably also 2 to 10% of ~ts derived from aclylic o~ me~acrylic aci~
In a fif~ aspect, ~e ~vention provides n~vel co~positions which c~mprise the 20 reaction product of (A) 30 to 90% of at leas~ one SCC polymer having a crystalline mel~ng point Tm (in dle composi~on) ~ 40 to ~()~, and (B) 10 ~o 70% o~ a~ least ol e ~norphous polymer which (i) cont~s a plurality of ~ups which react w:ith the SCC polymer, and (ii) has a molecular weight of 1,000 to 20?0009 e.g. a polyether, pa~ularly a polyedler selected from polyethylene oxide, polypr~pylene o~ide and pKDlytetrahydrofru~Ln.

In a sixd~ aspect, the invention provides novel compvsi~orls which comprise (A) 30 to 70% ~f at leas~ one SC: C polyrDeT having a molecular weight of 2,000 to 200?000~ and (B~ 25 to 70% of at least one polyme~ w hich ~i) has a melt index of 2 to 20Q
and (ii) is selected fro m polycapr~lactone and copolyrners consisting of units de~ived firom e~hylene and vinyl ac~tate and ~p~onally f~m one or mo~e other comonomers.

The novel compositions of the third,~our~, fifth and sixth aspects of the invention are useful as casting polymers but arc also usefulfo~ other purposes, for WO 93/21967 PCr/US93/03962 ~t '~-3 ~` J

example as temperature-sensitive coatings, e.g. on seeds, as pa~kaging materials, as molding compounds, and as hot melt adhesives.

DETAILED DESCRI~ION QF THE INVEN~ON
s Definitions~ Abb~iationa~Measurements In this specificat;on, parts, amounts and percentages are by weight. -Tempera~es are in C Molecular weights are weight average molecular weights ~:
expressed in Daltons a~ld are dete$mined by gel pem~ation chr~matography (GPC) in te~ahydrofilran CI~:). Frst order transition points (o~.ten referred to as lmel~ng points), glass transition points, and heats of fusion are determined by a Differential Scanning Cal~imeter (DSC) using the second heat cycle and a hea~ng rate of 10Cln~nute. The peak of the DSC curve is refe~ed to as T",. C~ystalliza~on ~5 temperanlres are deteImined by a DSC at a cooling rate of 10C/minute.

The "power" of a material is defimed as dle fc~rce requ~d to s~etch a l-inch (2.54 cm) wide sample of the material to twice its original leng~. Melt ~dex values are measured by ASTM Dl238 (modiffed). Tensile modulus values are calculated acc~ing to ASl~I D638 a~ testing the mate~ial by ASTM Dl708 at a crosshead speed of 1 inch/mi~ute (2.54 cml~ute). Strength values given herein are the ~ensile modulus of the mate~ psi) multiplied by the thiclcness of dle mate~ial (inch).
Streng~ values for casts above Tm are measured after heating ~e material to ~m +l0)C and allowing it oo eq~libra~e at that tempera~e for S ~nutes. Streng~ values for moldW casts are measurod at 2~C afte~ hea~ng the cast to a~ least ~m 1 1~)C, allo~g the cast to recover wi~out any res~raint (if it is heat-recoverabl~), cooling it to 25C and allowing ~e cast to equilibrate at 25C for 1 ho~. Air flow pe~neabili~(AFP) values gi~ren h~ are measured as fo31ows. An air gun is secured in a jig, and an anemometeT is placed ~ a reference posi~on at ~he centa of d~e air str~am at a distance of 5 inch (12.7 cm~ ~om dle tip of the gun. The gun is adjusted so that the air is cold and ~e air flow recorded by the anemometer is about l700 ft/min (570 mJmin).
A flat sample of the cast (or a corresponding sample -- see below) in the shape of a circle 2 inch (~.1 cm) in diameter, or a larger sample, is placed across ~e air flow at right angles to the air flow, at a dista~ce of S inch (13 cm) from the tip of the gun. The aLr flow is recorded by the ane~meter at three different SpOtS within about 0.5 inch ~1.2 cm3 of the reference position, and is averaged. The APP of the cast is the avera~e air flow, expressed as a percentage of the air flow without d~e cast. Since dle sample of ~ Wo93~21967 2.~3~2:~9 PCI/US93/03962 ' the cast must be flat, and the casts, both before and after molding, are usually not flat, it is usually necess~ry to measure A~;P values on corresponding samples, i.e. on sheets obtained by flattening out a portion of the cast, taking care not to ehange its porosity, or on sheets which are flat but which have otherwise been prepared in the same way as the S cast. For example, after measuring the APP of an unused sample using cold air, the air gun ean be adjusted to provide hot air whieh will effect reeovery of the sample, and the APP of the reeovered s~mple ean be measured.

Heat-recoverable Casts The preferred easts of the invention are, before use, heat-reeoverable. ~referably thdr ha~ liq result at least in part f~om the presenee in the east of an elas~ric support whieh is maintained ih a deformed ~usually stretched) eondition by the ridd easting polymer, and re~vers towards an undeformed config~ation when the 5 easting pobmer is softened by heating. However, the casts can also be heat-recoverable at least n part because the easting polymer, and/or a s~pport which fo~ns part of the east, is compo6ed of a crosslinked polymer which has been deformed above its melting point, and oooled in the deformed condidon; sueh a mate~ial, when heated above its melting ~, ~ pdnt, will tend to return to its undeformed condition.
Thç available recovery of a cast will depend on the extent of the deformation put into it. Preferably the cast, if beated to a temperature abo~re Tm~ in the absence of any restr~unt, ~ ~ecover so that at least one dimension d~ereof decreases from a first value -x to a second value y, where y is at mo$ 0.9~x~ par~cularly at most 0~75x. It is 25 generally unnecessary for y tO be less than 0.3~x, and in most cases y is more than 0.45x.

C~ PQ1Vme~
The easting polymers used in this inven~ion preferably have a Tm of at least 40C, particularly a$ least 45C, to ensure that the cast does not soften under n~
a$mospheric ~ondidons. It is also prefe~d that Tm is no more than 60~C, par~cularly no more than 55C, so that the casting polymer will soften and can be molded at lemQan~s which do not cause distress to human patients. Mel~ng preferably takesplace ove$~arange of less than 20C, particularly less than 15C, especially less than 10C, more cspecially less than 5C. If the casting polymer is a polyolefin, it preferably consists essendally of a single tactic fonn, i.e. is wholly atac~ic or syndiotactic or ~ ~ .

wo 93/21967 ;~ Pcr/uS93/03962 isotactic, so that its melting point is sharp. Particularly when using polymers with Tm's of 40-60C, it is preferred that rec~ystallization should take place rapidly on cooling from above Tm to below Tm, so that the patient does not have to remain still for an extended time while the cast hardens; we have found that excellent results are s obtained in practice if, when the cast is heated above Tm and then cooled to CIm - 10)C
at a rate of 10C/min, the castîng polymer~ecrystallizes not more than 2 minutes, preferably not more than 1 minute, after it has cooled to Tm . The recrystallization temperature of the polymer is preferably about 35 to 55C. Casting polymers having Tm's above 60C, e.g. polycapr~lactone-based compositions, can benefit from many of 10 our discoveries, but greater care is needed when using them, since it is usually necess~y (in order to prevent distress to the patient) to effect at least some of the molding of the cast at a ~e which is below Tm but at which the polymer has not ye~ recrystallized For those polymers, eherefore, it may be disadvantageous for recrystallization eo take place very rapidly on cooling from above Tm to below Tm.

Preferred casting polymers for use in the present invention comp~ise crystallinepo!yms in which the crystallinity results exclusively oq~ p~edominandy fr~m side chains which are attached to the polymcr backbone. Such polymers are often Iefe~ed to as sidc chain crystallizable polymers, or SCCst and include polymers containing units derived 20 from (or derivable from) one or more monomers such as substituted and unsubstituted acrylates, fluoroacryl~tes, vinyl esters, acrylamides, malei~des, ~lefins, ~aLkyl styrenes, aLkyhrinyl ethers, alkylethylene oxides, triglycaides (e.g. tristearin and pentaerydlritol tetras~ea~ate)t allcyl phosphazenes and amino acids; polyisocyanates;
polyurethanes; and polysiloxanes; as described for ~xample in J. Poly. Sci. ~Q, 19 2s (1962), J. Poly. Sci, (Polymer Chemistry) Z, 3053 (1969), ~, 1835, 3349, 3351, 3367, 10, 1657, 3347, 18, 2197, 19, 1871, J. Poly. Sci, Macromol. Rev, 8, 117 (1974), Macromolecules 12, 94 (1979), 13, 12, 15, 18, 2141, 19, 611, JACS 75, 3326 (1953), ~; 6280, Polymes J ~, 991 (1985); and Poly. Sci USSR 21, 241 (1979).

3d SCCs for use as casting polymers in this invention can be broadly defined as polymers which comprise repeating units of the general formula I where Y is an organic radic21 forming part of a polymer backbone and Cy comprises a crystallizable moiety and is prefelably prcsent in amount such that the SCC has a heat of fusion of at leàst ~0, prefailbly at least 40; Joules/gtam. The crystallizable moiety may be connected - ~ 35 to the po!yn~r backbonc direct1y or through a divalent organic or inorganic radical, e.g.

, ::
, ~

W O 93/21967 ~ ~ 3 ~1 2 1 ~ PC~r/US93/03962 an ester, amide, carbonyl, carboxy, amino, hydrocarbon (for example phenylene), ether or thioether link, or through an ionic salt linkage (for example a carboxyaLkyl ammonium, sulfonium or phosphonium ion pair). The radical Cy may be aliphatic or aromadc, for example aL~cyl of at least 10 carbons, fluoralkyl of at least 6 carbons oq ~aL~cyl styrene s wherein the aL~cyl contains 6 ~o 24 carbons. The SCC may contain two or mo~e different epeating units of this general formula. The SCC may also contain other repeating units, but the amount of such other units is preferably such that the total weight of the crystallizable moieties is at least twice the weight of the remainder of the polymer.
lo Preferred SCCs comprise side chains containing in total at least S times as many carbon atoms as the polymer backbone, par~cularly side chains comprising linear ~ polymethylene moieties containing 12 to 50, especially 16 to 22, carbon atoms. The SCC may also contain units derived ~om one or more other monomers, e.g. othe~ cyl acrylates, metha~ylates (e.g. glycidyl methacrylate), a~ylamides and methacrylamides;
15 acrylic and~me~ylic acid$ acrylarmde; methacrylamide; maleic anhy~ride; 2~
cyanatoethyl metha~ylate; comonomers containing a~mne groups, styrene; vinyl acetate;
monoa~ylic functional polystyrene; ethyl vinyl ether, vinyl chlonde; hydroxya~l acrylates and methacrylates; aL~coxyalkyl acrylates and me~acrylates; and derivatives of polyethylene glycl~l with molecular weights ~om 50 to StO. Such other monomers are 20 gene~ally present in total amount less than 50%, particularly less than 35%, especially less than 25%, e.g. 0 to 15%. They may be added to modify the melting point, modulus, MV~, or other physical properties of the SCC, or to provide si2es for crosslinking.
One example of an SCC is an SCC consis~ng essentially of units derived f~m 2s ~100% hexadecyl acrylate (Cl~A~ o octadecyl acrylate (C18A) and ~20% of one or mo~e of acrylic acid, methacrylic acid, itaconic acid, maleic an~ydride or a similar monomer providing a eure site on ~e copolymer.

~he SCC may also be rca~ted with one o~ more other materials which produce a 30 strengthened material, fo~ ~xample a multifunctional agent such as amine-t~ated propylene ~xide, polyethylene oxide, polytetrahydr~furan and polybutadienes containing hydroxyl groups, di-, tri- or multifunctional acrylic or methacrylic esters, vinyl ethers, esters and amides, isocyanates, aldehydes and epoxies.
3S The SCC may also be reacted with anodler polymer, or fo~med on another polymer, so that it is present ?S one of the blocks in a block copolymer. Such block copolymers are described fo~ example in Inte~national Patent Application No.
- PCI/US92/08508 filed October 6, 1992 and copending conNnonly assigned US

WO 93/21967 PCr~US93/03962 ~ ~ '3 ~

Application Serial No. (Docket No. 9213.2) filed April 14, 1993, the disclosures of which are incorporated herein by reference. An SCC polymer as described above can provide the hard block, with the soft block being provided by an amorphous block having a Tg less than ~m - 10)C or a crystalline block (which may S also be an SCC block) having a melting point TmS less than (Tm - 10)C. Alternatively, an SCC polymer as described above can provide the soft block, with the hard block being provided by an arphous block having a Tg greater than (Tm + 10)C or a crystalline block having a melting point Tm}, greater than (Tm + 10)C. Suitableamorphous blocks are well known in dle art and include polyethers, polystyrene, 0 polyacrylates, polyesters and polyurethanes.
The molecular weight of the casting polymer is generally more than 5,000, and when it is the so~e polymeIic ing~edient of the casting con~position is preferably at least 50,000,.particularly at least 100,000. When the casting polymer is a block copolymer 15 containing SCC blocks, its lecular weight is preferably more d~an 25,0~0, especially more than 75,000, with the molecular weight of each SCC block pref~rably being 2,50~ to 20,000.
The cas~ing polymer can be crosslinked by radiation or chemical crosslin~ng 20 methods known to those sldll~d in the art. Radiation crosslinking can be effected, for exa~le~ by an eleceron beam o~ Cobalt 60 radiation. Chemical crosslin~ng can be effected, for example, by means of peroxides or silanes, by ionic crosslinking, or with the aid of mulifunctional agents as des~ibed above.

25 stin~QnW-~
The casang composition can contain, in addition to ~e casang polymer of mel~ng ~nt Tm~ one o~ more addidonal polymers and/or one or more non-polyn~ric ingredients, e.g. inorganic fillers~ plasticizers, an~ioxidants, processing aids, and 30 pigments, for exa~le carbon black, graphite, glass fibers, Kevlar fibers, sil*a, talc and calcium carbonate.

Conventional SCC polymers tend to have poor physical p~op~rties, and this limits their value as casting polymers. SCC block copol~mers and strengthened or35 crosslinked SCC polymer have better physical properties, but require additional preparative steps. We have d~vul that improved physical properties can be obtained by blending the SCC polymer with an appropriate additional polymer. The wo 93/21967 ~ ~ ~? (Si 2 ~ Pcr/US93/03962 resulting composi~ions are useful not only as casting polymers but also for other purposes, e.g. as hot melt adhesives, packaging materials, seed coa~ngs, etc.
Furthermore, many of the compositions are novel per se and as such fonn part of the present invention, in par~cular the compositions set forth above as the third, fo~h, J fifth and sixth aspects of the invention.

We have obtained particularly good results by making use of an SCC polyrner which contains at least 309to of units denvable from at l~ast one n~ l acryl~te or methacrylate in which the n-alkyl gr~up contains 14 to 50, preferably 18 to 30, especially 20 to 24, carbon atoms and 7 to 65%, prefe~ably 9 to 60%, especially 18 to 42%, of units derived rom a high Tg monomer, i.e. a monomer which, if homopolymerized, gives a polymer having a Tg which is at least (Tm + 10)-C, preferably at least ~m + 20)-C, especially ~t least 8û C, but which is p~eferably not more than 120-C particularly not mo~e than lOO-C. The prefe~r~d higb Tg monomer is styrene; other high Tg monomers include a-methyl styrene and other aromatic compounds cont~ing vinyl groups, methyl methacrylate, ethyl methacrylate, t-butyl acrylate and phenoxy ethyl a~ylate. The SCC can also contain up to 15%, p~efera-bly up to 10%, e.g. 2 to 7%, of units derived from othe~ monomers, preferably acrylic acid. The molecular weight of the p~lymer is pqeferably 25,000 to 5~0,000, particularly 5G,0~ to 200,000. Such an SCC polymer can have a su~prisingly high modulus, often more dlan 40,000 psi, ~28,000 kg/cm237 a sharp melnng point, low melt viscosi~y and good re~yst~lliza~on ldne~cs.

The pr~ es of such an SCC polymer can be yet furth~r improved, in p~cular its impact s~ng~ can be incIeased, by ~ing wi~ it a ~andom ethylene copolymer which comprises at least 30% ~ units deriYed from e~ylene and 7 to 70%of uni~s d~ived from at lease one e~ylenically unsa~ted monomer contaLning at least one polar group. The eompatibility ~f these polyme~s is highly surpnsing. The ethylene copolymer is preferably an ethyleneJvinyl acetate copolymer containing 1~ to 60~o, particularly 26 to 42% of units derived ~rom vinyl acetate, and preferably also containing 2 to lO~ro of units de~ived fr~m acrylic acid. Tlle raio of the SCC polymer to the ethylene polymer is preferably from 0.2$ to 5, pa~icularly 0.5 to 4.
J

The blends just described are par~cul~ly valuable examples of blends which 35 comprise an SCC polymer and a second polymer which improves ~e physical p~oper~es of the SCC polymer. l'hus we have discovered that imp~oved physical proper~es can Wo 93/21967 ~ Pcr/US93/03962 s~;? 10 often be obtained by blending an SCC polymer with at least one compatible olefinpolymer, especially an ethylene/vinyl acetate or ethylene~vinyl acetateJacrylic acid copolymer. Good results are obtained when the SCC polymer contains units derivedfrom acrylic or methacrylic acid, pqeferably in amount 2 to 10%, par~cularly 3 to 7%, S and has a molecular weight of less than 15,000, preferably less than 10,000, and the EVA polymer contains 25 to 50%, preferably 28 to 35~o, of uni!s derived from vinyl acetate; particularly good results are obtained when the EVA polymer also contains units derived f~m acrylic or methacrylic a~id, e.g. in amount 2 to 10%. Other olefin polymers which can give improved physical prope~es include other edlylene copolymers, 10 including ethylene/vinyl chloride, ethylene/acrylic acid, ethylene/ethyl acTylate, ethylene/butyl acrylate, and ethylene/methyl ac~ylate copolymers. The mDcture can also contain an ionic component, e.g. a zinc acrylic acid complex.
Another way in which the physical proper~es of SCC polyrners can be improved 15 is by blendi~g them with polycaprolactone (PCL) o~ er cyclic ester polymer asdisclosed in U.S. Patent NQ 3,692,023. PCL and the related polyeste~s have melting points which are too high to pennit their use in casts which are heated after application to ~e pat;ent, and they also take a long ~me to crystallize ~e~ cooling below Tm.
~, However, we have found dlat mixtures of SCC polymers and PCL can have a Tm 20 substantially below that of the PCL on its own, without undue broadening of ~e melting ~ange. Preferred SCC polyme~s for this puspose comprise units deTived ~rom C16A
and/or C18A, and op~onally units derivable ~om one o¢ mo~e other monomers selected f~om n-alkyl acryl~tes and medlacrylates in which the alkyl group con~s less than 18 carbons, acrylic acid, me~acrylic acid, a~ryl~de, alld me~acryla~. Particularly 2s p~eferred SCC polymers are C16A/C18AJAA copolymers.

As briefly indicated above, dle casdng compositions can contain a wide varie~y of fille~s and o~er non-pol~c ingredients. However~ we have found d~at certain fille~ give better ~esulls dlan odlers, in par~cular in improving the modulus and/or 30 ~ elongation of the composition, or the balance between modulus and elonga~on, particularly wi~ casting compositions containing an ethyleneh~inyl acetate copolymes in addition to an SCC casting polymer. We have ob~ned particularly good results ~rough the use of calcium carbonate (both untreated and surface-treated), wollastonite (acicular calcium silicate,~ and talc (magnesium silicate).

WO 93/21967 ~ 3 ~ Z 1 ~3 P~r/US~3/03962 Supports The novel casts preferably comprise a support for the polymer, par~icularly a woven, knitted, braided or non-woven fabric, OF other flexible strucnlre. The support 5 preferably has, in the cast before it is molded, an open s~ucture which assists in the heat transfer be~veen different parts of the cast, and which, in the finished cast, remains sufficiendy porous to ensure that the support has a high moistur& vapor transmission rate (MVl~) and thus does not prevent the subslrate fiom "breathing".
When a support in a heat-recoverable cast has an open s~uc~ure, the si~e of the apeltures therein will decrease dunng recov~y. Recovery will also make the suppo~t -~
mo~e ri~ Thus the cross-sectional area of the components of dle support will r~o~mally increase d~ng recovery, and previously scparated c~nponents will come closer together and be bonded togetheT by ~he cas~ing polymer.
When the unused cast is heat-recoverable, the support must not prevent the des~ed recovery, and prefe~ably ~e support is itself reco~erab!e. The sup~rt preferably comp~ises an elastic material which is held in a defoq~ned state by the solid casting polymer, but which recove~s towards an undeformed state when the cas~ng polymer softens. Altemadvely, the SUppMt can be a c~osslinked polyme~ic article 20 which has been d~formed above its mel~ng point and cooled in the defoqmed state, ~us rendenng the ar~cle heat~ ve~able if it is again heated above its mel~ng point.
The support is preferably elas~cally deformable~ In a fabnc, el~s~city can res~lt ~om the construc~aon of the ~ab¢ic andJor the inherent elas~city of ~e fibers Iher~in.
25 For exa~le, a support which can be used in this inven~ion can be a knitted fa~ic prepared entirely from a glass fiber y~n. How~ver, prefeITed supports a~e fabncs, parhcularly knitted ~abr:cs, in which at least ~ne of the yarns is composed of an elastomeric mat~ial. ~e fab~ic may be isotropiç o~ have elastici~r or other proper~es which ~/ary directionally. Preferably ~e support can be s~etched elas~ally in at least 30 one direction by at least 25%, preferably at least 50%, e.g. 50 to 125%, based on the co~responding dimension of the suppor~ in its uns~etched state. For example, thesuppo~t can be a knitted, woven or braided material which comprises an elastomeric yarn, e.g. a segmented polyurethane yarn, or a natural or synthetic rubber yarn,preferably with a non-elastomeric yam, e.g. a glass ~lbe~, graphite, polyamide or 3S ~polyarylene ya~n, which is selected tQ give the cast desired strength or other physical properties. Suitable support matenals are described for example in US Patent No.4,668,563 (Buese), and are available commercially, for example nylon/segmented WO93/21967 ~3-- 12 PCI/US93/03g6~

polyurethane fabrics and glass fiber/segmented polyurethane fabrics. The power of the fabric is preferably 0.1 to 2.0 lb/inch (18 to 360 glcm). The support preferably has, at least after stretching, an open stn~cture~ so that the coated support ~i.e. the cast) can also have an open stracture~ as further described elsewhere in ~is specification.
A cast which is flexible bef~re it has been molded, and which contains a support which is not elastomeric, can be made by (1) bonding the casting polymer to a frangible support, e.g. a woven or non-woven glass fiber fabnc, and (2) deforming the resulting composite so as to break sufficient bonds between ~e casting polymer and the 10 support to make the com~osite sufflciend,v flexible to be wIapped ~round the substrate.

When d~e cast is heat-recoverable, it is desi~able that the recove~y forces should 15 be sufficient to ensure adequate con~ormance of ~e cast to the substrate, but not so high as to damage the subsaate, or cause pain, or reduce blood flow. The power of the cast, in the direction of recove~y, is, ~erefore, p~eferably 0.1 to 2.0 l~rmch (18 to 360 g/cm). Similarly, when the lding of the cast is effecte;d al least in part by ex~Lemally applied forces, e.g. ~om the or~hopedist's hands, ~he cast should be easily lded but 20 ~ in cohesive. The strengdl of the cast, at the time o~ molding, is the~
preferably 0.05 to 5, par~ :ularly 0.1 to 3, especially 0.25 ~ 2, pounds per inch.
PaTt oQ all of dle interi~r surface of the cas~s o~ ~e inven~on can be coated with an adhesive. The adhesive can be ~or example a temperature-ac~vated adhesive as ~5 described in Inte~na~onal Applica~on No. PCI US90/02223 ~Docke~ No. 9433~l-P~), or a pressure-sensidve adhesive (PSA), for example a PSA as discl~sed in IntcrDational Patent Application No. PCI US9~)l 153 (Docket No. 921 l.l-PCI ) filed Pebrualy 12/ 1992, c~ng priority from US Patent applica~on Senal No.
07/82g,494 filed February 12, 199l~ or in US Applica~on S~ial No. _ (Oocket 30 No. 9213.2) ISled Ap~il l4, 1993, par8cularly a PSA containing an SCC ~lymer additive which Ieduces the adhesive streng~ of the PSA when the PSA is warmed.
1 he use of such an adhesive is o~ten par~cularly desirable when the cast suIrounds a finger and needs to resist removal by the patient (such casts are oft~n referred to as "Mallet Finger" casts) by laIs~inating such a sheet to a support.
When the cast comprises a sheet of the casting composi~ion or is made by laminating such a sheet to a support, the sheet is generally l to 5 mm thick, wid~

WO 93/21967 ~ .1 3 ~ 3 P~r/US93/03962 smaller thicknesses, e.g less than 2 mm, being preferred for smaller casts, e.g. for fingers, toes and hands.
We have found that the casts are much easier to apply, without overhea~ng s which can cause distress to the pa~ent or ~e orthopedist, if ~ey have, before molding, an ~pen stluc~e which permits rapid and unifolm heating of the cas~ng composition, especially when using a hot air gun to heat ~he cast. The open s~ucture is prefeMbly such that over substantial areas of the cast, par~icularly over the whole of the casting polymer, heating dle cast with a hot air gun causes a difference in temperature, between 10 the inside and the outside of ~e cast at any particular point, of not more ~an 15C, pardcularly ~IOt more than 10C, e~ally not re th0n 5~C. We have obtained excellent results unth casts which, befo~e molding have an air flow permeability (AFP) of at least 10%, particularly at least 20%.
When an unused cast is molded into its finished state, any apernlre$ ~erein willbecome smaller (or disappear completely) as a ~es~t of recovery and/or the~noplastic flow of dle casdng polymer. However, it is ve~y desirable ~at the finishetl cast should re~ a sufficiendy open seruct~e t~ allow the substrate to "~readle", i.e. should have a good moisture vapor transmission ra~e (MVTR). It is, th~eforc, preferred ~at the20 apertures in the unused cast should re~ sufficiendy large in d~e finished cast to provide this benefit. We h~ve found dla~ the AFP of the finished cast is p~eferably at least 1%, more preferably at least 2%, pamcularly at least 5%, especially at least 8%,.
On the od~er hand, d~e large~ the size and the numbe~ of apertures in dle fînished cast, the weaker and less water-resistant it will be. Preferably, dlere~ore, ~e Al;P of the finished 25 cast is less ~an 25%, more preferably less thall 20%, p~eularly less ~a~ 15%,~specially less ~an 10%. The p~eferred upper values for APP in ~e unused cast are somewhat higher (because ~he aperh~s become smaller during n~lding of ~e cast). The AFP of the unused cast is preferably less than 45%, more prefe~ably less than 35%, par~icularly less than 30%, espe~ally less than 25%.
The size and number of dle apertures in dle unused and finished cast are important in deterrmning the ease with which the cast can be applied and its pe~fonnance. We have obtained excellent results using apertuIes having an a~ea from 0.01 to 0.08 cm2, prefe~ably 0.02 to 0.06 cm2, e.g. about 0.04 cm2. `
Whal a cast is prepar~d by laminating together two or more porous components, e.g. by wrapping 2, 3 or 4 thicknesses of a porous sheet matenal, the perfo~nance of the cast reflects the porosity of the individual components so that when WO 93/~19~7 ~3 ~, C~ Pcr/VS93/03962 .

a cast is prepared in this way, the sheet material pre~erably has an A~;P of at least 15%, particularly at least 25%, but less than 60%, par~cularly less than 40%, especially less than 30%.
s It is desirable that the cast should become relatively in~lexible in a short period after molding is complete. Preferably, therefore, the casting composition, as it cools, changes f~m a moldable composition to an inflexible composition ove~ a temperature range of less than 10C, par~cularly less than 5C, and preferably does so in less than 2 minutes, particularly less than 1 minute. The casting polymer need no~ over all of its crystallinity in o~er for dle cas~ng composition ~ becon~e substandally inflexible. In ~is s~cation, the polymer can be regarded as having cooled to a crystalline inflexible matenal if its crystallinity is at least 0.5 X, where X is the cryst~llinity of the polymer after it has been cooled ~om above Tm to ~m-10)C and mainta:ined at ~m -10)C foq four cTystalliza~on half lives.
1s After it has been molded and has then co~led, dle cast should be s~ g and relatively inflexible. The cast ~refe~ably has, therefore, a strengeh of more ~an 5, parti~ularly more dlan 10, espe~ially more dlan 15, pounds pe~ inch. The pIessure exerted by ~e finished cast on the substrate should be low cnough to pre~rent damage d~eTe~, eidler immediately or while the cast is being worn (e.g. swe~ling"~lce~s, tissue neurosis and dec~eased blood flow), and may be fo~ example 10 40 ~n Hg above atmosphesic.
~e casts of the inven~on can take n~ny fo~ns, including (1) non-recoverable tapcs and sheets which are heated and ~lded Ln place by the or~opedist; (2) elas~c tapes and sheets which are not ~ecoverable but which are heated and then stretched by the or~opedist as ~ey aTe applied to a subs~ate; (3) rccoverable tapes and sheets which are flexible enough to be wTapped around a subs~atc while they are cold and are then heated and ~cove~ fo~rn a cast; and (4~ rela~ively rigid heat-recoverable casts which are in appsoximately ~e desired final shape, but sufficiendy ove~size to allow the cast to be pla~ed around ~e substrate, and which are placed around the substrate and therl heated to recover onto the substrate. To assist in fit~ng such a preshaped cast to dle substrate, and/oq to assist in its later removal f~m the substrate, the cast may comprise (1) a first component which (i~ has an open cross-section and (ii) comprises ~e cas~ing polymer, and (2) a sec ond component which (i) ~orms a closal cross-section with ~e fflstcomponent and (ii) is elastorne~ic when the article is in its ~lrst (recoverable) configuraion and/or when ~e anicle is in its second (fftted) configuration. The second component can be secured to the first component a~te~ the first component has been fned, or a casting t~` ~ WO 93/21967 ~ t 3 '1 2 Fl t) PCI/US93/03962 polymer can be applied to part only of an elastomeric suppor~. Alternatively or additionally, the cast can be in the foqm of two or m~re parts which can be fiteed together ar~und the substrate and secured together bef~re heating begins. One or more of the component parts can carry means for securing the parts together, preferably means which S permit the size of the cast to be adjusted, e.g. hook-and-lvop closures of the kind sold under ~e t~ademarlc "Velcro".
Pre-shaped casts may have a wide variety of shapes, including for example a cylinder for use as a ~mger splint, a bent cylinder to surround an ankle~ knee or elbow, 10 or a glo~e to swround part or all of a hand.

Pre~araPon o(~as~n~ C:o~positiQns and Casts The cas~ng compositions used in dlis invenhon can be prepared by ~g 15 procedu~es well known in the art, and can be fo~d or applied to SUppOItS by proced~es well known in ~e art, e.g. as solutions in organic solvents which a~ removed by drying, or as molten compositions, e.g. by melt exlrusion onto dle support or by hot laminaaon.
Where the suppor~ is an dastic SUppMt, the casti~g composi~on is preferably applied to tl~e non~efon~ed support, and the composite then s~etched e.g. over a mandrel or other 20 form, wlile the casting co~sidon is at a temperature abo~e Tm~ followed by cooling with dle support in its stretched condition. However, the casting composi~on can also be applied to the stretched suppo~t and solidified on it. After the com~osition has been applied to a support, it may be desirable to hea~ it, at a t~nperan~ well above Tm~
prefe~ably with press~e, to ensure dlat it fully pene~rates d~e support. It may also be 25 de~ble to bl~w air duough the casting composi~ion to ensure that dle open strucnlre of a us suppor~ is no~ filled up by the casting polymer.

,~
This invention is illus~ated in the ~vllowing Examples, in which ~he ~ollowing abbreviations are used to refer to the compounds and materials set out in par~ntheses after the abbrevianon:

AA ~acrylic acid), C4A (butyl acrylate), C14A (tetradecyl acrylate), Cl6A (hexadccyl acrylate), C18A (octadecyl acrylae), C22A (docosanyl a~rylate), I~IMA (me~yl methacrylate), C4MA (bu~yl medlacrylate), C18MA (octadecyl ~thac~ylate), GMA
(glycidsl methac~yhte~, ETGMA (ethyl ~îglycidol methacrylate), STY (styrene), C12SH
(dodecyl mercaptan), XAMA (a polyfuncaonal crosslinlcing agent sold by Hoechst WO 93/21g67 Pcr/US93/03~62 `?~L3 16 Celanese under the trade name Xama 2), ESP570 (t-amylperoxy 2-ethyl hexanoate), ESP
5100 (t-amylperoxy benzoate), JT and JD (polyfunctional amines sold by Texaco under the ~rade names Jeffamine T-3000 and Jeffa~ne D4000, respectively), PCL
(polycaprolactone sold by Polymer Sciences under the trade name PClh40),.ELV40, s ELV150, ELV240, ELV250, ELY4260 and ELV4320 (different grades of ethylene/vinyl acetate copolymers sold by E. I. duPont de Nemours under the trade names Elvax 40, Elvax 150, Elvax 246, Elvax 250, Elvax 4260 and Elvax 4320 respectively), EY901 and EY902 (different grades of ethylenefYinyl ace~ate copolymers sold by Quantum Chen~cal Co. Inc. under the trade names Vynathene EY901-25 and EY 902-35 respectively), HEP
(heptane), TOL (toluene), NL Knit (a knitted fabnc which contains about 85%
- - polyhcxamethylene adipamide (nylon) fibers and about 15% segmented polyurethane (Lycra) fibers, has a thickness of about 0.023 cm (0.0~5 inch) and a weight of about 95 g/m2, has a linear stress strain curve at extensions up to about 126%, and exhibits a power of about (0.75 lbrmch), GLF (0.75) and GLF (2.0) (E-type non-woven random glass fiber mats whi`ch have weights of about 0.022, 0.044 and 0.06 glcm2 (0.75, 1.5 and 2.0 oz/sq - ft) respecdvely, sold by Tap Plastics), GRAPH (a non-woven graphite mat sold under the trade name Panex CPF by Stack~ole), GL Knit (a warp knîtted fabric which contains glass fiber yarn and an elastic yarn, which has a weight of about 530 g/m2, and which is available from Carolina Narrow Pabric Co., Winston-Salem, North Carolina, USA), :~ 20 DAB9 (calcium carbonate sold by United Minerals ~o. under the ~ade name DAB9), W-30 (Wollastonite sold by R. T. Vanderbilt Co. under dle trade name W-30), and Nytal (talc sold by R. T. Vanderbilt under the trade name Ny~l 400).

SCC Polvmers The first step in the Examples was to make SCC polymers Sl to S23, using the nomers and amounts thereof specified in Table 1 below. The monomers were placed in a vessel widl a suitable ~olvent, and optionally with azobisisobutyroni~aile (AIBN) as an initiator and/o~ C12SH as a chain transfer agent. These ingredients were heated under nitrogen, with sti~ing, at an elevated temperature, e.g. 60-70C, for an appropriate time, e.g. 12-20 hours. After cooling, the SCC polymer was precipitated by pouring the reaction mixture into ethanol. Por example, in preparing polymer S1, the monomers and 0.5 g AIBN were dissolved in lS0 mL toluene, and heated at 70C for 12 hours. In preparing polyn~s S3-Sll, the n~ns were dissolved in sufficient toluene to give a reaction mixtme containing 42% mono~ners, and the reaction mixture was heated at 60~C for 16 :: hours. In prepanng polymer S12, the monomérs, 0.05 g C12SH, and 3.5 g AIBN were dissolved in a mixture of 1400 ~ heptane and 80 mL ethyl acetate, and the reaction ` W O 93/21967 2 ~ PC~r/US93/03962 mixture was hea~ed at 60C for 20 hours. In preparing polymer S20, 1700 g of a mixture of C22A, STY, AA and Cl2SH ~ra~io 60/371310.19) was maintained at 105C while adding a blend of the same mixture (6800 g) and ESP570 (42.5 g) over 90 mins; ESP 5100 (42.5 g) was then added over 45 mins, while raising the temperature to 140C; and this5 temperature was maintained for a further 230 minutes. Polymers S21-23 were made in a similar way.

Examples l-lS
In Examples 1 l~O 15, the next step was to p~epare the fabric suppDrt, using thefabric designated in Table 2 and as further des~ibed below. The fabric suppo¢t was then ~ contacted with a co~position cont~ing the ingredients and amounts theseof set out in Table 2 and processed as f~er described below.

~.~The NI, Knit fabric was sewn into a tube of diameter about 1.6 cm (0.63 inch)having maximum elasticity in the r~al direction. ~he fab~ic tu~e was fitted over a mandrel of diameter l.9 cm (0.7~ inch), a~d was then coated with ~e SCC polym~r com~sition, w}~ch also contained 25 parts of heptane as solvent. After ~e sQlvent had been removed by heating, the weight of polymer deposited on the fabric was about 1 g. pe~ inch of ~e 20 tube measured in the axial direction. lhe coated tube was Te~noved from the mandrel and retained its expanded shape. It could be easily deformed, for exarnple by pressing into a flat sleevc. Two 7.6 cm (3 inch) lengths were cut f~om the tube. One length was placed ovcr ~ finger, and then heated wi~ a hair dryer, causing it to shrink and fit snugly over the finger. The second leng~ was pl2ced over the first, and likewise shrunlc. After 2 minutes, 25 the two lengths had hardened in~o a composite c~st which imsnobilized ~e finger but did not res~ict its blood flow. The cast was later reheated, when it became soft and flexible, so that it could be removed, or the fing~r and cast could be repositioned into a different shape, e.g. a bend; after two minut~s dle cast had again cooled and hardened, immobili~ng the ~mger in its new shape.
Example 2. A s~p of the NL Knit fabric was stretched about 50% and coated with the SCC polymer composition, heated at 90C for 2 hours, and cooled. A first sample of the resul~ng flexible coated fabnc was wrapped around a finger and then heated; dle fabric softened and shrank snugly around the finger, and on cooling fonned a rigid cast, with the 35 overlapping parts of the fabric adhering to each other, which immo~i~ed the finger but did not restrict its blood flow. A second sample was heated and then wrapped around a finger, using light tension; on cooling, the fabric formed a rigid cast which immobiliæd the finger W O 93/21967 ~ 3 PC~`/US93/03962 but did not restrict its blood flow. A third sample was used in the same way as the first, but greater tension was used when wrapping; on cooling, the resulting cast was uncomfortably tight, and restlicted blood flow.

5 Examp!e 3. In each of Examples 3A, 3B and 3C, the dry SCC ~olymer was placed on top of the GLF fabric, and the fabric and polymer were heated between sheets of siliconized release paper in a press at 100C and 14 kg/cm~ (100 psi). The ratio by weight of fabric to polymer was about 1.5. The resulting composites were stiff at temperatures below about 39C, but flexible at temperanlres above about 42C.
- ~le 4. A sample of the composite of Example 3C, about 10 x 10 CIIl (4 x 4 inch), was laminated between two sheets of a polyester the~moplastic elastomer ("Hy trel" 4056) about 0.0025 cm (0.001 inch3 thick. The laminate was cut into the shape of a nose splint, warmed with a hair dryer to make it flexible~ and foImed over a nose. After cooling, it 15 provided a iigid nose splint.

Exam~le 5. Another, larger~ sample of d~e composite of Example 3C was laminated be~ween 0.0044 cm (0.00175 inch) ~ick polyester film ("Medifilm 325" f~orn Bertek3 and a 0.0025 cm (0.001 inch~ ~ick film of polymer S12, which is a temperan~ responsive 20 adhesive. The resulting composite was rigid and non-tacky at room temperature. It was cut into the shape of a Vilinus nose splint, waImed with a h~ dryer to malce it flexible and to make the adhesive tacky, and then fo~med over the nose and forehead of a person. A~te~
cooling, it pr~vided a rigid splint bonded to dle nose and foreheadO

25 Example 6A. The NL Knit fabqic was sewn into a tube abou~ 91 cm ~36 inch) long and about 1.4 cm (0.55 inch) in diameter. The outside of ~e tube was coated ~nth the SCC
polym~ solu~ion, which also contained toluene (30 parts), and then dried at 135C for 3 hours. The coating weight was about ~5 g/m2. The coated tube was cut into 10 cm (4 inch) len~hs whîch were heated with a hot ais gun t~ malce dlem flexible and then 30 expanded by lOO~o over a mandrel, and cooled on ~e mandrel. A first expanded length was placed over a finge~ and then heated with a hair d~yer, causing it to shrink and fit snugly over the finger. A second expanded leng~ was placed over the first and likewise shrunk, fom2ing a comp~site cast which was significantly stronger than the cast produced in Example 1. A 2.5 cm (1 inch) length of the coated tube was cut lengthwise so that its 35 mechanical properties could b~ m~asu~ed. At 25C, the fabIic was inelas~c and had a strength of about 1430 g/cm (8 lb/inch). At 50C, the fabric had a power of about 204 g ` ` wo g3,2l96, 2 l ~ PCI/US93/03~62 ~

(0.45 lb)~ was reversibly elastic, and exhibited a linear stressls~ain curve of about 100%
elongation.

Example 6B. The NL Knit fabric, in flat sheet foIm, was coated with the SCC polymer solution and then dried at 13~C for 3 hours. A 21.5 x 2~ cm (85 x 11 inch) of the coated fabric was folded in half, and then cut and sewn so thae it comprised a first tube about 10 cm (4 inch) long with a diameter of about 6.3 cm (2.5 inch), and a second tube about 6.3 cm (2.5 inch) long widl a diameter of about 1.9 cm (0.75 inch) which cornmlmicates with the first tube and is at ~n angle of about 60~ to it. This structure can be heated, expanded while hoe, and cooled in the expanded sta~e. l~e resul~ng s~ructure is a cast which can be - placed over a hand to cover the wrist, part of the palm of the hand and the thumb, and which, when heated with a hair d~yer, shrinks and foq~ns, after cooling, a rigid cast whieh ~bilizes the dlumb.
Example 7.~ One of the expanded lengths produced in Example 6 was lighdy coate~ on the inside with a 30% solution of ~e S12 SCC polyn~r, which was a ten~e~ature-responsive adhesive. After it had been dried, the adhesive was non-tacly at room t~mperature. l~e adhesive~oated length was placed o~fer a finger and ~en heated with a hair dryer, causing it to shrink and t~> fonn, after cooling, a ngid cast bonded to the finge~.
ExamDle 8. Thc graphite fabnc was coated with the SCC composi~ion, which also contained toluene (30 par~s) and ~en dried at 140C for 2 hours. The coating weight was about 201 g/m2 (0.132 g/inch2). A coating abou~ 0.0025 em (0.001 inch) ~ick of the S12 SCC polymer adhesive was fo¢sr~d Oll a polyester thennoplasac elastome~ ("Hytrel" 4056) film 0.0045 ~n (Q.00175 inch) thick. The coat~d fabric a~d the coated film were larninated together, w~th the SCC polymers in c~ntactO To the other side of d~e graphite fabric was bonded a 0.0051 cm (0.002 inch) thick film of an acryli~ pIessure-sensitive adhesive sold by Monsanto Chemical as a solution under the trade name Gelva 737. l he resultant composite was rigid at room temperature; when wanned with a hair ~yer, became flexible and could be confcn~ned a~ound a substrate; and a~ter cooling provided a rigid pr~tec~ve shell bonded to ~e substrate. For example, a rl~5 x 7.5 cm (3 x 3 inch~ sample ~ ~e composite was used in this way to provide a ~igid molded protective cast bonded to a person's heel.
Example 9. The blend of the Sl SCC polymer and dle PCL was made by melt mixing at 100C. The blend had a Tm of 44C and a rec~ystalliza~ion temperatu~e of 34C; a sample of it 7.6 x 10.1 x 0.076 cm (3 x 4 x 0.03 inch) could be wanned with a hair dryer tO a WO93/21967 ~ .'1,\i3 20 Pcr/uss3/o396~

temperature at which it was flexible, could be wrapped arouncl a finger, and allowed to cool, when it formed a rigid cast around the finger. The PCL on its own had a Tm of 60C
and a r~rystalliza~ion temperanlre of 23C; a similar sample of PCL on its own, when heated to a temperature at which it was flexible, could not be wrapped around a finger S because the finger could not tolerate the heat.
Examples lOA and lQB. A sample of S3 SCC polymer was heated to 100C for S n~inu~s and placed on a metal blo~k maintained at 32C. The SCC polymer began to harden after 20 seconds and was fully hardened after 60 seconds. The PCL polymer, sin~ilarly treated, began to harden after 90 seconds, and was not fully hardened until after 4 IInnutes.

amDI~ 11. The blend of S1 SCCpolymer and the PCL was n~de by melt mixing. The blend has a Tm of about 42C. The blend was hot melt coated onto the 1~ Knit fabric, and cooled. A sample about ?.5 x 10 cm (3 x 4 inch) was Cllt fr~m the coated fabnc; walmed 1~ in water at 60C, thus rendenng it flexible; and wrapped around a finger. After coolLng for 3 r~utes, it provided a rigid splint around the finger.

Exam~le 12. The coated fabric of Example 3B was laminated between two sheets of polyurethane film 0.0044 cm (0.0017~ inch) thick. ("Tuftane" 4056, sold by Lord Co~pora~on, Erie, Pennsylvania), each sheet being coated on its inner surface with a laye~
of an acrylic pressure-sensitive adhesive (Gelva 737). The resulting la~nate was rigid at room temperature. Howev~r, by exer~ng sufficient force, i~ could be wrapped ar~und a 0~63 cm (0.25 inch) mandrel, ~us firacturing the rigid parts of the laminate, and making it possible to wrap the l~ate ar~und a person's WliSt. The wrapped laminate was heated with a hair ~}ryer, dlus softening the l~ate, and then allowed to cool, when it fom~ed a rigid splint around the WliSt.

Example 13. The soluaon of the SCC polymer ~5 parts of one r>f the polymers S3 to S1 ldissolved in 5 parts of toluene) was coated onto the NL Knit fabnc so ~at the weight of the soludon was 40 6(Wo ~f ~e weight of the uncoated fablic and heated at 135C for 4 hours. The cooled composites were inelastic at room temperatu~e, but were flexible and could be s~etched by up to 509ro when heated to 50C. When the slretched composite was cooled to room temperature, it again became inelastic. For example, 2.5 x 10.2 cm ~1 x 4 inch) strips were ssretched about 50% at 50C; cooled in the stretched state; loosely wrapped around a 1.25 cm (0.5 inch3 mandrel; and heated to 50C. The s~ips recovered, ~viding a rigid, protec~ve coating confo~ning to the mandrel, with overlapping sec~ons of the strips adhered to each other.

wo 93/2.g6, ~ ~ ~ /1 2 1 Y P~/USg3/~3962 Example 14. Several 7.6 cm (3 inch) lengths were cut from the expanded tube of coated NL Knit fabric prepared in Example 6, and a layer of a medical grade pressure-sensitive adhesive in the f~nn of a ~ansfer tape ("Avery I-780" available from Avery Dennison) was applied to the outside of the lengths. Strips 2.5 cm (1 inch) wide were cut lengthwise from S the lengths. These strips recovered when heated, and became inelastic when cooled. For example, one strip was applied to loose sldn on a person's bicep. When the strip was heated with a hair dryer, it contracted, pulling under the s~ip togethe~ and uniformly stretching the sulT~unding skin. Thus a s¢ip of this type can be applied o~er a wound or incision and, when desired, heated to close and protect the wound or incision. A strip of 10 this type can also be used to stretch an area of skin, e.g. around a bmn.
Exam~le 15. The blend ~ S13 SCC polymer and Elvax 240 was made by melt mixing.
The polymers appeared to be completely compatible in the mel~ A san~le of ~e blend was melt pressed to a thickness of about 0.~127 cm (0.005 inch), laminated to the NL Knit fabnc at 100C, and allowed to cool. The laIrnnate was heated to 60C, stretched 100%, and cooled in the stretched state. When reheated, the stretched fabric contracted, and on cooling became rigid.
In Examples 16 and 17, d~e composition designated in Table 2 was p~epared and 20 used in the way described below.
Exam~le 16. The s~fied blend~s of SCC polym~ and Elvax were prepared by melt m~ing. In each of Examples 16A, B and D, the polymers appea~ to be completely compa~ble, and the blend colJld b¢ melted easily and molded on human s~dn to pro~ride a 25 protective coa~ing. Howeves, in Example 16~ e polymers were not compatible, and ~he blend did not soften sufficiently to be useful as an orthopedic device at tempe~atures which could be tolerated by human skin.
Example 17. The specified blends of S18 SCC polymer and Jeffamine in Examples 17A, 30 B, C and D were made by melt mixing. 50g samples of 2he Slg SCC polymer on its own (Example 17E) and of the blends (E~x~mples 17A, B, C and D) were mel~ processed into plaques and heated under pressure fvr 4 hours at 150C. At room temperature, Sample E
was opaque and very brittle. Samples A, B, C and D were strong and flexible at room temperature, and when heated to 40~C became soft and confo~nal. Sample C had a 35 desirable low melt modulus and high melt elonga~on. Sample D had a relaavely high melt modulus and relatively poor melt elongation. Sample B was transparent, so that a wound covered by it could be inspected without removing the sample.

Wo 93/219~7 Pcr/US93/03962 ';I~'L 3 ~ 22 Examples 18-24 In Examples 18-34, the ingredients and amounts thereof set out in Table 2 were made by melt mixing in a Brabender. The modulus and elongadon of the blends in 5 Examples 19-34 were measured In Example 22, the polymelic composition (S20 + EY901) was hot melt coated as a layer about 0.01 inch (0.025 cm) thick onto the GL Knit fabric. The coated fabric was maintained at 100C for 4 hours and cooled. The resulting composite was about 0.07 inch 10 (0.18 cm) t}~ick. The composite was then heated with a hot air gun to soften ~e polymenc composition, stretched 100%~ and cooled in ~e s~etched st~te. A sample of the cooled -~ - fabric, 12 by 48 inch (30.5 by 122 cm) (s~etched lengthwise) was wrapped 3 times around a metal tube of 12.7 cm diameter and the exterior wrapped end was bonded to the layer below with a polyan~de hoe melt adhesive. The wrapped fabric was heated to recover it ls onto the tube, and after cooling, the expanded cast was pulled off dle n~be. The cast was placed over a person's wrist and forearm, ~d heated with a hair dryel. It recovered fully within 100 seconds and after cooling provided a rigid cast.

WO93/21967 ;~ ,? 1 ii PCI/VS93/03962 ~ . ~ . ". ~, SCC ~LYMERS

Monomer~ S~ S2 S3 S4 S5 S6 S7 58 S9 S10 Sl l $12 AA 4 4 4 4 4 4 4 4 21.1 . _ _ . _ _ , _ _ . _ _ _ C14A _ 301 C18A _ 48 57 86 86 86 70 70 70 80 9() . : r l _ l _ ,, _ _ . - _ _ _ . ,, .
~MA _ 26 . _ _ _ _ . . . , _ _ _ ._ _ srY . 10 _ .
P~. _ _ __ . . _ Tm(Q 45 41 46 48 51 50 51 43 38 _ 42 45 _ 29 MWt(103D) 10 54 97 112 71 87 142 138 10 9 398 . - . ........ . . _ _ _ _ _ Mon~ S13 S14 S15 S16 S17 S18 Sl9 S20 S21 S22 S23 M ~; 3 4 5 4 2 3 3 3 _ .- . . . _ . . . _ C4A 10 _ 10 C16~ 40 48 _ . , . . . _ . ~ _ _ _ _ _ . . _ __ ..- _ _ _ _ _ _ _ _ _ _ C22A 60 68 80 ~5.6 ~ _ _ _ _ _ _ . r . = _ _ _ M~
G~A
E,T",GMA ,,, SI'Y 37 29 17 41.4 . _ _ _ _ _ _ _ _ _ _ . . .
~ . .,_ __ _ _ Tm(C ) 47 47 46 45 . 46 45 50 S5 47 MWt(103D) 9 5 .7 9 90 6.7 300 57 1 86 11 2 1 38 58 _ W O 93/21967 ~ PC~r/US93/03962 c~ ~3 `~ 24 T~UBLIE 2 C O~F~SrIIO NS A~n~ FA B RICS
. _ _ _ .
~x. CO~D~S~ON Modulus Elonga~on F~iBR~C
_ , _ .
No. SCC Cxh~ psi %
1~ Sl(25) XA M A(0!25) _ _ ~ _ _ NL Knit 3A S2(100! _ ~ _ _ _ . ~ _ ~ GLF(0.75 ~3B S2(100) _ ~ . . ~ GLF(l.S) 3C,4,5 S2(1003 _ . ~ _ GLF~2.0! _ 6 S3(25) _ ~5) - . ~ _ NL K~t _ 7 ~ S12(100? .~ . ~ ~ _ om Example6 8 S3 ~25) _ rT(~ _ ~ _ - . GRJUPH

9 . Sl(5) _ - ~ L (5) _ . ~ _ . . ~
10A S3(10D~ _ _ . . ~ . . - . ~ _ 10B S3(1 ) E3LV 240(6) _ __ _ ~1 '9~
12 S2(1W~ _ - r-- ~ . - ~xnE~unple3B
13 _ S3-S11(5) - . ~. _ ~DL Knit _ _ 14 _ S3(ioO) _ _ . _ ~ _. ~m Exanple6 _ S13(5) ELv24ots! _ _ . NE'Knit 16A Sl4(5) _ ELV240~5) .~ ; .. . ~ _ - _ _ _ 16B S15(5)_ ~ V4320(5) _ ~ - _ _ 16~ S16(5) ELVlS0(5) _ . ~ _ _ . -~. _ 16D S17(5) ~ Y2S0(5~ _ _ - ~ _ 17A . _ S18 ~ O _ rr(l5) _ _ _ . . ~. . _ - _ .
17B Sl~(80) _ (~0) _ _ - _ . ~ .
1?C S18(80) (20) _ =-17D S18(70) _ (30) _ - . ~ .
17E S18(100) . _ 18 S!9~50) - ELV4320(50) . . ~ _ incompadble 19 520~75) ELV40t25) 205 k 70 20 _ S20(80) _ LV40(2~L_ _225 ~ 38 _ 21 S20(?s) I~L~ aL____ 2l2 k 5~ .~ . . .
22 ~ ~ 338 k 27 GL Knit 23 S20~?5) !~Y2~ L _____ 2l2 ~ 2l 24 _ S21i75~ ~ ELV4~L~ _ - .
~ Q@Z~ 3~ 91____ 2lk 25 26 ~ L_____ ELV43 0~25~ 30k 3 ~ _ 27 _ S20(100~ _ 4~k 2.5 28 ~i2l~lL____ EY90 ~20i _ 34k 27 29 S20(60) E~LV4260(S20) 46~ k 24 __ _ ~ _ . . , _ . _ S20(54) ELV42~0(18~ 41.5 k 18 . DAiB9 ~? - -31 S20(54) ELV4260(18) 30.3 k 44 . DAUB9 ~ ) . _ 32 S20(58) ELV4260(~4~ 46 ~ 34 _ DAB9~8? . _ 33 S20(60) ELV426D(20) 37.4k 37 _ DAUB9~20) : . _ _ 34 S20~60) ELV~O~20) 34.6 k 37 DAiB9 ~ ) ..

~ Wo 93/21967 ~ Pcr/US93/0396 Example 25. An expanded cast made by the procedure of Example 24 was slit lengthwise. It opened up to a C-shaped cross-section. Opposite edges of a strip of NL
Knit fabric about 1.5 inch (3.8 cm) wide were sewn to the slit edges, securing them together and reclosing the tube. The resulting cast was placed over a person's wrist and 5 forearm, and heated with a hair dryer. It recovered, and, after ~ooling~ provided a cast which was sufficiendy rigid to prevcnt movement, but which could expand or contract to accommodate swelling oq shrinkage of the wrist o~ forearm and which could be removed~

Example 26. The procedurc of Example 25 was followed except that, instead of the10 fabnc strip, two halvcs of a zipper werc secu~ed to the slit cdges of the cast so that the . ` . cast could bc s~ed in place by closing the zipper.

Exan~le 27. The pn~e of Example 25 was fo!lowed except that, instead of the fabric strip, matching parts of a Velcro closure were secured to the inner and outer 15 surfaccs, rcspecdvely, adjaccnt thc cut edges, so that the cast could bc secured in place by pressing together thc matching pa1ts.
.
~amde 28. This cxample shows the advantagcs of a cast having an open structure.
In each of the tests rsported below, a flat sam~le of an unused cast was placed on a 20 metal screen below thc tip of a hot~air gun at a distance of about 3 inch /~7.6 cm) for samples 1, 2 and 3, and about 5 inch (12.7 cm) for samplcs 4, 5 and 6.
Themwouples werc placed on the top and bottom of the sample, and recorded the temp~an~ at 15 second ~te~vals as the sample was heated by a constant flow of hot air from the gUlt. The various samples used we~e:
1. A sheet of PCI, 0.03 inch (0.076 cm) dlick, without apert~es.
2. A composite about 0.048 inch (0.12 cm) thick obtained by melt la~nadng a sheet Qf PCL 0.03 inch (0.076 cm) thick, without ape~es, and a lulitt~d fibe~glass tape.
3. A composite about 0.06 inch (0.15 cm) thick obtained by lamina~ng ! two layers of composite 2 and expanding the laminate 100%; this composite was highly porous.
4. A sheet of the S20 SCC polymer about 0.043 inch (0.11 cm) thick, - . without npertures. ~ ~ ~
5. The e~ cmPS'te made in Example 22, which was highly , ~, , , ~
porous.
~-~ 6. The composite made in Example 22, before it was expanded.
,~ -, - ~ :

WO 93~21967 PCr/U~93/03962 ;~ 26 The results obtained are set out in Table 3 below, and clearly show the benefits of the open structure in samples 3 and 5, as compared to ~he non-porous structures of the other samples.

. ~. _ _ _ Tempe~ ~nlre of ~ ample (~ '? After (! ecs) O 15 30 4~ 60 90 . . . _ _ ....... ..
Sample 1 Top 27_ 61 67_ 62_61 . _ Bottom28__ 40 50 61*_62 -Sample 2 Top 26 ?3 78 76 78 _ Bottom25 48 54 62*63 -Sample 3 Top 26 70 78 -Bottom26 68* 79 -___ . . __ __ Sample 4 T~ 24 53 60 67 69 Bo~)m 23 36 41 47 52 63*
Sa~le 5 Top _ 23 68 71 71 _ __ Bon~m ~3 63~ ? 70 _ _ Sa~le 6 T~p 24 64 70 71 74 Bottom 25 42 62* 72 62 * At ~is time, dle ~ast was recovering andlo~ moldable ~O

Claims (6)

1. An article which is (a) suitable for use as an orthopedic cast, or can be converted into an article suitable for use as an orthopedic cast, (b) comprises a casting composition which comprises a polymer having a crystalline melting point Tm (referred to herein as the casting polymer), (c) has a first stable configuration at temperatures below Tm, (d) become moldable when heated to a temperature above Tm and adopts a second stableconfiguration when cooled to a temperature below Tm after being molded, and (e) has at least one of the following characteristics (1) the casting polymer has a Tm of 40 to 55°C, a Young's Modulus at 25°C of at least 22,000 psi (1540 kg/cm2) and a melt viscosity at 65°C of less than 8.5 x 105 poise.
(2) at least a part of the article is (i) heat-recoverable, and (ii) when heated to a temperature above Tm in the absence of restraint, recovers so that at least one dimension thereof decreases from a first value x to a second value y which is at most 0.95 x, (3) when the article is heated to a temperature above Tm and then cooled to (Tm-10)°C at a rate of 10°C per minute, the casting composition recrystallizes not more than 2 minutes after it has cooled to Tm.
(4) at least a part of the article has a plurality of apertures through its thickness, each of the apertures having an area of 0.01 to 0.08 cm2, (5) at least a part of the article has an air flow permeability of 10 to 35%, (6) the casting polymer comprises an SCC polymer, and (7) the cast comprises (A) a first component which (i) has an open cross-section and (ii) comprises the casting composition, and (B) a second component which (i) forms a closed cross-section with the first component and (ii) is elastomeric when the article is in its first configuration and/or when the article is in its second configuration..

2. A process for forming an orthopedic cast around a patient or for preparing an article which is suitable for use as an orthopedic cast, which process comprises (A) heating an article according to claim 1 to a temperature above Tm at which the article is moldable;
(B) molding the article while it is at a temperature at which it is moldable, into a second configuration, and (C) cooling the article to render the second configuration stable.

3. A polymeric composition which comprises (A) a random copolymer which comprises (i) at least 30% of units having a crystalline melting point (in the copolymer) of Tm °C and derivable from at least one n-alkyl acrylate or n-alkyl methacrylate wherein the n-alkyl group contains 14 to 50 carbon atoms, and (ii) 7 to 70% of units derived from at least one monomer, said monomer being one which, when homopolymerized, results in a homopolymer having a glass transition point Tg which is at least (Tm +10)°C, and (B) a random copolymer which comprises (i) at least 30% of units derived from ethylene and (ii) 7 to 70% of units derived from an ethylenically unsaturated monomer containing at least one polar group, the ratio of A to B being from 0.25 to 4.

4. A polymeric composition which comprises (A) an SCC polymer which has a molecular weight of less than 15,000 and which contains 2 to 10% of units derived from acrylic or methacrylic acid, and .
(B) an ethylene/vinyl acetate copolymer which contains 25 to 40% of units derived from vinyl acetate.

5. A polymeric composition which comprises the reaction product of (A) 30 to 90% of at least one SCC polymer having a crystalline melting point Tm (in the composition) of 40 to 60°C, and (B) 10 to 70% of at least one amorphous polymer which (ii) contains a plurality of groups which react with the SCC polymer and (ii) has a molecular weight of 1,000 to 20,000.

6. A polymeric composition which comprises (A) 30 to 70% of at least one SCC polymer having a molecular weight of 2,000 to 200,000, and (B) 25 to 70% of at least one polymer which (i) has a melt index of 2 to 200 and (ii) is selected from polycaprolactone and copolymers consisting of units derived from ethylene and vinyl acetate and optionally from one or more other comonomers.